Rib Wreck

Diver measuring large vertical iron ribs from a shipwreck buried in sand
Photo: Brenda Altmeier/NOAA

The Rib Wreck gets its name from iron reinforcing frames that project from the sand covering the site. These frames give the appearance of a rib cage from a large animal. The Rib Wreck is approximately three-quarters of a mile off Vaca Key and one half mile southwest of Key Colony Beach in the Middle Florida Keys. The site has an average depth of 14 feet and is located in the intermediate shallows between Hawk Channel and the inshore tidal flats off Marathon.


Based on measurements of the hull's architectural dimensions and characteristics, the Rib Wreck was determined to be a large wooden hulled sailing vessel with iron reinforcement. The ship's design dates it to the later half of the 19th century. This style of construction was developed to take advantage of the strength of iron reinforcement of wooden framing. Iron reinforced ships were produced in greater numbers from European shipyards. American shipyards continued to build vessels with limited iron reinforcement of wooden framing as the timber and skilled workforce to work it was still available and cost effective. No cargo remains were found at this site and valuable portions of this ship's rigging and machinery were not found. These valuable items were likely salvaged, leaving a bare hulk. Like many abandoned wrecks in the warm, shallow Florida waters, the superstructure and upper works disintegrated quickly while shipworms ate portions of the lower hull that were exposed. Storms may have shifted the wreckage shoreward before it sank into the sand and began to stabilize over time.


The Rib Wreck is oriented north-northeast by south-southeast (240° magnetic north) with neither bow nor stern distinguishable. The majority of the site lies in a scoured sand pocket surrounded by seagrass. The rectangular iron reinforcing frames are the most obvious feature of the site protruding to between 1 and 5 feet above the sand. Ten of these frames were recorded in line and appear to be attached to the wooden hull structure beneath the sand. Other features recorded include tapered pipes and collars, and other iron objects or potential frames lying on the sand around the site. Planking and framing was measured and recorded as well as concretions, ballast fragments, and a brick fragment. Several rings and collars were located near the southern terminus of the keelson. The rings are C-shaped, of various thicknesses, and range from a few inches to almost 2 feet in diameter. A large, grooved collar or gear was partially buried in the sand among the rings.

The lack of any significant ballast may indicate that it carried a cargo of rock, cement, or iron as ballast at the time of grounding and this material was salvaged for use. No indication of sailing tackle or of steam power was obvious without further investigation, but the lack of such may also indicate the Rib Wreck was converted to an open barge at a later stage. The iron frames protruding from the site retain the shape of a deep draft vessel and not the flat bottom profile of many working barges.

(McClarnon et al., 2007)

Site Map

Archaeological drawing of the shipwreck
Rib Wreck site map. Credit: Florida Bureau of Archaeological Research